The technology of Touch Screen Panel (TSP) in Cell is to manufacture a TSP sensor and a driving circuit thereof on an array substrate using an array process. The TSP sensor is integrated with a liquid crystal cell of a Liquid Crystal Display (LCD) panel so that the product is light and thin and has versatile functionalities. Therefore, the reliability of the TSP is effectively improved.
FIG. 1 (a) and FIG. 1 (b) shows a basic light sensitive TSP in Cell circuit in prior art. As shown in FIG. 1(a), the sensor senses light using a photodiode D1 and generates electric leakage to detect a touch signal. As shown in FIG. 1(b), the sensor senses light using a sensitive capacitor C2 and detects the touch signal by the coupling of the sensitive capacitor and the change of the capacitor. Thin-Film Transistor (TFT) T1 functions as an amplifying transistor to amplify the voltage change across D1 after detecting the touch signal, increase the capability to driving the output of the TSP in Cell circuit, so that an external readout circuit for TSP may correctly read out the detection result.
Compared with a traditional liquid crystal panel, an Active Matrix Organic Light Emitting Diode (AMOLED) has characteristics of rapider response, higher contrast ratio, and wider angle of view or the like. Pixels of AMOLED are driven to emit light and display by a related driving circuit on the array substrate. FIG. 2 is a diagram showing an embodiment of the AMOLED pixel unit circuit.
If the TSP in cell circuit shown in FIG. 1 (a) or FIG. 1 (b) is simply integrated into the AMOLED pixel unit circuit as shown in FIG. 2, except for the existing five TFTs and two capacitors, three TFTs and one capacitor is required to be added, and except for the existing three control signals and two power sources, three control signals are required to be added to the control signal lines. However, the pixels of the AMOLED do not have enough space for the addition of these TFTs and signal lines. Therefore, in the prior art, the TSP in Cell circuit cannot be integrated into the AMOLED pixel unit circuit.